Problem: Solve for $q$ : $-20 = q - 24$
Explanation: Add $24$ to both sides: $ \begin{eqnarray} \\ \hphantom{-20 {+ 24}} &\hphantom{=}& \hphantom{q} \\ -20 &=& q - 24 \\ \\ {+24} && {+24} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -20 {+ 24} &=& q \\ \end{eqnarray} $ Simplify. $ q = 4$